With rapid progress in human genomics and identification of disease associated own or foreign genes, gene therapy approaches look increasingly promising for treating human diseases, including cancer and AIDS. To avoid bottle-necks, rapid progress is needed in developing efficient gene transfer vectors. Among the available vector systems, lentiviral vectors are specially well suited for gene transfer into non-dividing cells, including stem cells. Exploiting our considerable expertise in human lentivirus (HIV-1 and HIV-2) gene regulation, we have designed novel HIV-2 vectors which have certain advantages over previously designed HIV-1 vectors. We have undertaken a comparative study of the packaging efficiency, gene-transfer ability, and biological safety of HIV-1 and HIV-2 vectors. Because animal models for them exist, we have chosen four model genes and disease entities: Bax gene in neuroblastoma representing a signal transduction target, AADC gene in Parkinson disease representing a biochemical pathway defect, alpha-glactosidase gene in Fabry disease representing an in-born error of metabolism, and chemokine gene in infectious disease representing HIV infection in AIDS. We are also using these vectors for antigen delivery as DNA vaccines against HIV infection and AIDS, plasmid DNA as a prime and vector as a boost in prime-boost strategy. In addition, ex vivo transduction of dendritic cells looks to be a useful strategy for invoking cell mediated immune response. Certain proinflammatory chemokines can inhibit HIV infection as this virus uses chemokine receptors as co-receptors to gain entry into the target cells. The M- tropic viruses use CCR5 and T-tropic viruses use CXCR4 as co-receptors and are inhibited by the corresponding CC and CXC chemokines. Using eukaryotic expression systems (e.g., HIV-2 vectors)to express recombinant chemokines, and focussing on their defined structural elements (flexible coils, beta sheets and alpha helix), domain mapping studies revealed some elements necessary and others dispensable for antiviral activity. Unexpectedly, mutational analysis has uncovered regions of the chemokine molecule critical for its stability and transport prompting the hypothesis of the existance of epitopes and conformational states critical for the life of the chemokine. These studies should allow the design of a chemokine molecule composed of minimal functional domains modeled on CC and CXC chemokines and effective against both M- and T-tropic HIVs. - Gene Therapy, Vectors, Lentiviruses, Chemokines, AIDS, DNA vaccine,